The present invention relates to a modular catch pan for wellheads and method of use of the same.
U.S. Pat. No. 5,634,485 (1997 Holtby) entitled xe2x80x9cMethod and apparatus for retrofitting drilling rigs with a catch panxe2x80x9d describes a drilling rig catch pan consisting of two mating sections. It also describes a manner of mounting the catch pan to a wellhead positioned below the drilling rig floor in order to prevent environmental contamination. When the Holtby apparatus was used in the field, it was discovered that for different wellhead configurations, the preferred position of the apparatus would vary. For some installations the apparatus was placed below a rotating head, on others on a spacer collar below the rotating head, on others below a hydril, on others on a flow nipple above the flow line, and on others on a flow nipple below the flow line.
The present invention relates to a modular catch pan that provided greater flexibility to adapt to different installation dimensions.
According to one aspect of the present invention there is provided a modular catch pan for wellheads which includes a rigid pan body consisting of two detachably coupled sections, the body having a circular opening. A plurality of split annular adaptor collars are provided. Each of the adaptor collars has the same outer diameter so that any one of them can be fitted into the circular opening. Each of the adaptor collars has an outer circumferential sealing surface adapted to form a seal with the circular opening of the body. Each of the adaptor collars has an inner circumferential sealing surface. The size of the inner circumferential sealing surface and the distance of the inner circumferential sealing surface from the outer circumferential sealing surface varies between adaptor collars.
According to another aspect of the invention there is provided a method of use of a modular catch pan for wellheads. A first step involves providing a modular catch pan as described above. A second step involves selecting one of the plurality of adaptor collars to suit an intended installation application. The one selected will have a desired size of inner circumferential sealing surface positioned a desired distance from the outer circumferential sealing surface.
Instead of carrying a large inventory of catch pans, each with a different size of circular opening, a single size of catch pan is used in combination with an adaptor collar with dimensions to suit the intended installation.
The best known mode of applying the teachings of the present invention includes the following preferred features.
It is preferred that the adaptor collars be made from compressible foam. When the adaptor collars are compressed into position an effective seal is made along both the inner circumferential sealing surface and outer circumferential sealing surface.
It is preferred that the adaptor collars each having integral clamps adapted for clamping the adaptor collar around the wellhead. Using the integral clamps one of the adaptor collars can be clamped into the desired position on the wellhead and thereafter mated with the pan body.
It is preferred that the adaptor collars each have substantially circumferential top and bottom flanges. This both ensures that the outer circumferential sealing surface does not shift and enhances sealing of that surface.
The foam seal does not have the same rigidity as did the seal assembly used in U.S. Pat. No. 5,634,485 (1997 Holtby). It is, therefore preferred that the pan body be suspended by lines for additional support.